WOULD YOU LEAVE your dining room window wide open all winter? Not preparing your house for the season is the equivalent of doing just that, according to Bill Stack, the energy-efficiency spokesman for the utility company NSTAR. “People can relate to that analogy,” Stack says. Most can also relate to the Department of Energy statistic that making your home more airtight and efficient can save you up to 25 percent on utility bills. Another benefit: Winterizing can stave off later repairs, according to Angie Hicks, cofounder of the consumer website Angie’s List. “We hear this time and time again,” says Hicks, “that a lot of big emergency calls are really the result of skipping out on basic maintenance: cleaning gutters, keeping the roof in good shape, insulating, caulking. Sometimes they take a little bit of time, but they’re not typically real expensive items, and some are things you can probably do yourself if you just know what needs to be done.”

Knowing what needs to be done and doing it, of course, can be different matters. But even if you’ve neglected winterizing your home until now, there’s still time to get enough work in that it will be buttoned up for those frigid days to come.

CAULK TRIM AND BASEBOARDS

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“For the typical homeowner,” says Brian Kimbel, a department supervisor in the Natick Home Depot, “just dealing with drafts you can feel will be a major improvement.” The first step? Ross Spinelli, a commercial sales specialist at Lowe’s in Woburn, recommends moistening your hand with water and running it along the edges of interior window and door trim and at the top of baseboards on exterior walls. “You’ll feel a draft like wind blowing through a straw,” he says. Caulking that space can make a significant difference. An eighth of an inch might not seem like a very big gap, but multiply it by, say, 1,000 linear feet of baseboard, and it adds up to more than 10 feet of space in your house that air can travel through. “If that’s not caulked, that’s a big, long, continuous gap,” says Steven Strickland, president of Earthworks Group, planning and design consultants in Murrells Inlet, South Carolina. “We tend to throw money at the problem in the form of heating oil, but all of that heat will just escape out of the envelope [around the house] until we start sealing the envelope.”

According to the US Department of Energy, as much as 35 percent of the air leakage in a home can come from small openings in doors, windows, and fireplaces. If your storm door jiggles or doesn’t close firmly, you’re losing that insulating pocket of air between it and the exterior door. Most storm doors have an adjustable strike plate — that’s the metal tab with a hole in it that’s mounted on the jamb — and simply moving it up or down a fraction of an inch can keep the door from blowing off its hinges in a sharp wind.

Door sweeps — long metal or rubber extensions that are nailed on to close the gap between the bottom of the door and the flooring — should be installed on basement and attic entries as well as on exterior doors.

Test your door for gaps, Spinelli recommends, by closing it on a dollar bill and then trying to pull the bill out. “If it slides out easily,” he says, “you’re losing money through that door.” Add stick-on rubber weatherstripping around the edges for a tighter seal.

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READY THE WINDOWS

Simply locking your windows can not only discourage burglars but also keep the cold wind out. “In a huge number of the houses I visit,” says Ian Rex, owner of The Energy Hound, a certified energy auditor in Beverly, “the windows are open about 2 millimeters at the top, and the homeowners can’t see it.” Turning the latch, he says, “sucks the two panels together so they’re sealed.” If your window locks don’t align properly, check the top pane — it may just need to be pushed up a bit.

If you have older windows you never open or patio doors you don’t use, there are two ways to seal them for the season. One is by applying clear weatherstripping tape along the edges; it’s effective at keeping cold air out but doesn’t damage the finish on walls or windows when it’s removed. The second option is to cover unused egresses with window film. Frost King, 3M, and other companies make this product for a little less than $20 a package, and though it may not be beautiful, it does help keep winter outdoors, where it belongs. Apply it with the double-stick tape provided, then use a hair dryer to shrink it tight.

Remove any window-mounted air-conditioning units. If that’s not practical because of the unit’s weight or for storage issues, or if you have a wall-mounted AC, purchase a cover for it. But, cautions Rex, “just buying something that goes over it doesn’t do anything unless it’s sealed at the edges.” He prefers weatherstripping tape for the job.

TEND TO THE FIREPLACE

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Close the flue in your fireplace when it’s not in use. “It’s amazing how many houses I go into in winter and think, ‘It’s really cold in here,’ and the flue’s open,” Rex says. He recommends putting a sticky note on your fridge on nights you have a fire. That way, in the morning, you’ll remember to close the flue.

Even when the flue is closed, it’s not a snug seal, so it’s still a heat-loss point. The best way to keep your fireplace airtight is to have a contractor install a glass door with vents at the bottom. “It’s energy-efficient, and you still have the comfort and ambience of a fire,” says Rex.

CHECK YOUR HEATING SYSTEM

In homes with forced hot-air heating, it’s important to change the filters annually. If the ductwork in your basement or attic is coming apart at the seams, seal it up so heat cannot escape — but don’t use duct tape. “Ducts are the only thing you do not use duct tape on,” says Kimbel. “It gets crisp and brittle and falls off. Use metal-foil tape instead.” Ducts do need to be sealed, Rex adds, but “much more frequently I’m finding gaps in the registers.” He recommends removing the vent cover and using spray-foam insulation like Great Stuff to close cracks between the ductwork and flooring, walls, or ceilings.

If your ducts haven’t been cleaned in 100 years, now might be a good time to do that, too. Angie’s List can put you in touch with 267 companies that professionally clean air ducts in the Boston area, 39 of which are “top-rated.”

According to Hicks, maintaining your furnace or boiler should be a priority. “The most common reason for emergency calls,” she says, “is failure to do maintenance in the fall. A furnace tuneup is only $75 or $100.” Realtor Gabrielle Daniels, with Coldwell Banker in Sudbury, agrees. “It’s a phone call to your heating company,” she says. “They will come out and service it properly, replacing any missing parts or fixing anything that’s broken, so it’ll operate most efficiently during the winter. Emergencies happen on Friday at 5 o’clock, but if you make that call, you might lessen the possibility.”

For boilers, consider asking the technician to install a reset heating control, which can increase efficiency by differentiating between colder and milder weather. It costs from $300 to $400 but can save as much as 10 percent on your heating bill. National Grid offers a $225 rebate on such a device, but you must obtain a “Web Submission ID” number from the utility’s website before installing it.

Daniels also urges you to use your winter tune-up time to change the batteries in your smoke and carbon monoxide detectors.

All of our experts advise getting an EnergyStar programmable thermostat if you don’t already have one; it can automatically turn the heat down while you’re out of the house. For installations made before January 1, 2013, Mass Save, an initiative sponsored by the state’s electric and gas companies to help residents and businesses manage energy expenses, offers a $25 rebate, and with the cost of most models under $60, says Spinelli, “you’d probably get your money back in the first year.” It’s a simple thing to do, involving only two or three wires, and at least one manufacturer, Honeywell, “provides a phone number you can call, and they will hold your hand through the whole process,” says Kimbel.

LOOK AFTER WATER SYSTEMS

Like the furnace or boiler, your hot water tank should be checked before you go into winter, but in this case you can do it yourself. If the thermostat is set at more than 120 degrees — the safety point that can keep children and the elderly from being scalded — turn it down. “Instead of finding your perfect shower temperature by mixing overly hot water with cold at the tap,” Rex says, “just set your hot water heater so it comes out at the right temperature.” According to the Environmental Protection Agency, this simple fix can save you from 6 percent to 10 percent on your water-heating costs.

Rex and Kimbel also point out, perhaps surprisingly, that buying a “blanket” to put around the hot water tank is not a good return on investment unless your tank is more than around 15 years old. “If you put your hand on it and it feels warm,” says Kimbel, “it’s worth putting the blanket on. But the new EnergyStar heaters have better insulation and don’t need it as much.”

Foam-wrapping the pipes that run from your hot water tank can help, but only, Rex advises, if the insulation is sealed at the edges. “Otherwise the air within seeps right out,” he says.

Speaking of water, Steven Roy, a principal at Elliot Whittier Insurance in Danvers, points out that many New England homeowners end up with claims because of frozen pipes. He discovered why himself when the pipes froze under his kitchen sink in a new house he lived in a few years ago. “The house was only like five years old when we bought it,” he says, “but the way the kitchen plumbing under the floor was situated — too close to the wall — the pipes would freeze.” When outdoor temps were frigid, Roy would simply leave the under-sink cabinet open to warm the air around the pipes. But if you have any cold spots in your house or basement, he recommends investing in a freeze alarm, an easy-to-install box you place near your pipes. It costs about $150, and, again, can save you that emergency call everyone dreads.

Finally, Daniels reminds that now’s the time to make sure hoses, sprinklers, and irrigation systems are drained and turned off for the winter.

READY YOUR ROOF

Ice dams can form on your roof and prevent the water from melting snow from draining. The water can then back up and damage shingles, leaking into the roof and causing serious damage to your home’s interior. You can avoid ice dams by first cleaning your gutters of any leaf debris before the temperature dips below freezing. Then, once the snow starts to fall, remove it from your roof with a long-poled roof rake. “I get the snow right off of there,” says Roy. “It is a pain, but not as painful as having water damage to ceilings and light fixtures and all of that.” Daniels recommends buying a roof rake now, “before they’re as hot as Springsteen tickets.”

A more involved but long-lasting way to prevent ice dams is to insulate your attic. “A rake is an effective temporary fix,” says Kimbel, “but it’s like bailing out your bathtub with a bucket instead of fixing the clogged drain.” The root cause of the problem, he says, is that warm air from the house can get to the roof and melt the snow toward its top; when the melted snow reaches the eaves, which are colder because they overhang the house, it can refreeze and back up, again causing damage to the shingles. If the attic is well insulated, however, the entire roof will remain the same temperature, and snow will melt only when the sun gets warm enough.

Rex points out that insulation alone, however, won’t solve the problem: You must also seal the entrance to the attic to prevent heat from the house from getting in. If you have a walk-up attic, simply add a weatherstrip sweep to the bottom of the door; if you have a hatch with a fold-down ladder, line its perimeter with stick-on foam weatherstripping.

ADD INSULATION

Cold air may be sneaking in around the electrical boxes that house outlets or switches in your exterior walls, but fixing this problem couldn’t be easier. A ¼-inch or even ⅛-inch gap is the equivalent of a 2-inch hole in your wall, according to Strickland. “That’s a hole in the envelope that’s supposed to surround your home so that cold air can’t come in,” he says. Kimbel notes that pre-cut foam gaskets are available for about 20 cents apiece. “It’s a two-minute job,” he says. “Simply remove the switch-plate screws, place the sealer over the outlet or switch, and reinstall the switch plate.”

Next up, check the basement rim joist, which separates the wood frame of your house from the foundation. If it’s not insulated, a lot of warmth can escape. “Keeping the heat from being lost from the basement helps keep that first floor warmer,” says Kimbel, “so when you’re standing in the kitchen barefoot in the morning, it’s not quite as excruciating an experience.” Nailing foam board with an R-value of 2 to 3.5 to the rim joist and then spraying foam insulation at its edges is the best fix.

Three-season rooms and enclosed porches can be major sources of heat loss if they’re not properly insulated. Working in the crawl space is a dirty job, but worth it. “On the bottom of the sun porch floor,” Rex says, “attach rigid foam board to the floor between the joists. Seal it with canned spray foam around the edges. It’s an easy fix.” Do the same in your garage if it’s located under your house, advises Spinelli. “Otherwise,” he says, “you’re basically sitting on an ice cube.”

If you’re willing to tackle a more involved project, consider having insulation blown into your exterior walls. “It directly saves on heating bills,” Kimbel says, “and increases comfort in the home.” This project requires a skilled contractor and can be pricey, but if you start with a free two-hour home-energy assessment from Mass Save, you can get a rebate for as much as 75 percent of the cost, up to $2,000.

In addition to providing rebates on insulation and energy-efficient hot water tanks and thermostats, Mass Save offers loans with zero percent interest when you install qualifying energy-efficient improvements such as solar hot water systems and replacement windows. You can get up to $25,000 with terms as long as seven years.

According to a 2003 study by the Harvard University School of Public Health, as many as 46 million homes in the United States are under-insulated. Start now and yours won’t be one of them.

Elizabeth Gehrman writes frequently for the Globe Magazine. Her book Rare Birds, about the Bermuda petrel, was released in early October. Send comments to magazine@globe.com.